Tamper-proof container

ABSTRACT

A sheet includes an optical fiber extending across at least a portion of its surface to detect a breach or nuclear radiation. The sheet can line at least a portion of a container or a fence. A breach of the sheet or radiation within or near the sheet reduces optical transmissibility of the fiber. The fiber integrates the radiation over time and/or over the length and volumetric mass of the fiber, making the fiber sensitive to even low-level radiation. The optical fiber is monitored for a change in its transmissibility. A reduction in the transmissibility, such as to below a threshold, can trigger an alarm, such as an annunciator, or send a message that includes information about the time or the container&#39;s contents or location when the breach or radiation is detected to a central location, such as a ship&#39;s control room or port notification system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/981,836, titled “Tamper Proof Container,” filed Nov. 5,2004, which is a continuation-in-part of U.S. patent application Ser.No. 10/837,883, titled “Tamper Proof Container,” filed May 3, 2004. Thisapplication claims the benefit of U.S. Provisional Application No.60/535,449, titled “Tamper Proof Container,” filed Jan. 9, 2004.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(Not Applicable)

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to security systems for shippingcontainers, boxes and the like and, more particularly, to such securitysystems that can detect tampering with, or breaches in, surfaces of suchcontainers or nuclear radiation from materials stored in the containers.

2. Description of the Prior Art

Cargo is often shipped in standardized containers, such as those used ontrucks, trains, ships and aircraft. Smaller units of cargo are typicallyshipped in cardboard boxes and the like. It is often difficult orimpossible to adequately guard these containers and boxes while they arein transit, such as on the high seas. In addition, some shipmentsoriginate in countries where port or rail yard security may not beadequate. Consequently, these containers and boxes are subject totampering by thieves, smugglers, terrorists, and other unscrupulouspeople. A breached container can, for example, be looted orsurreptitiously loaded with contraband, such as illegal drugs, weapons,explosives, contaminants or a weapon of mass destruction, such as anuclear weapon or a radiological weapon, with catastrophic results.Alternatively, a nuclear or radiological weapon can be loaded by a roguestate or terrorist organization into such a container for shipmentwithout necessarily breaching the container.

Such breaches and weapons are difficult to detect. The sheer number ofcontainers and boxes being shipped every day makes it difficult toadequately inspect each one. Even a visual inspection of the exterior ofa container is unlikely to reveal a breach. Shipping containers aresubject to rough handling by cranes and other heavy equipment. Many ofthem have been damaged multiple times in the natural course of businessand subsequently patched to extend their useful lives. Thus, uponinspection, a surreptitiously breached and patched container is likelyto appear unremarkable. Furthermore, many security professionals wouldprefer to detect breached containers and radioactive cargoes prior tothe containers entering a port and possibly preventing such containersfrom ever entering the port. The current method of placing a seal acrossthe locking mechanism of a container door is of limited value, whetherthere is a physical breach of the container or not, because the nuclearor radiological weapon could be loaded by terrorist as legitimate cargo.For example, the terrorists could circumvent or corrupt inventorycontrols and cargo manifest delivery systems using unscrupulousconfederates. A single breach or circumvention of a cargo deliverysystem by whatever means can have catastrophic consequences.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention can detect a breach of the interiorsurface of a shipping container or box or radiation from a source withinor near the container or box and can then trigger an alarm or notify acentral monitoring location, such as a ship's control room or a portnotification system. At least one liner sheet lines at least a portionof at least one interior surface of the shipping container or box, suchthat a breach of the portion of the interior surface also damages theliner sheet or radiation from a source, such as a nuclear orradiological weapon, impinges on the liner sheet. Such a liner sheet canalso be attached to other perimeter surfaces, such as fences or buildingwalls, to detect breaches of the surfaces or radiation near thesurfaces. The liner sheet defines an optical path extending across atleast a portion of the sheet. The optical path is monitored for achange, such as a loss or reduction of continuity, in an opticalcharacteristic of the optical path or a change in a characteristic ofthe light signal, such as a frequency or phase shift. If the container,box interior or other monitored surface is breached or the optical pathis irradiated, one or more portions of the optical path are affected andthe optical path is broken or altered. For example, a breach of thecontainer or box can break the optical path. Alternatively, radiationcan reduce or alter the light transmissibility of the optical path. Thedetected change in the optical path can be used to trigger an alarm,such as an annunciator or cause a notification signal to be sent to amonitoring station via any of a wide variety of existing networks, suchas the Internet and/or a wireless telecommunications network. Inaddition, a detailed accompanying message can provide information aboutthe nature of the breach, time, location, cargo manifest, etc.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

These and other features, advantages, aspects and embodiments of thepresent invention will become more apparent to those skilled in the artfrom the following detailed description of an embodiment of the presentinvention when taken with reference to the accompanying drawings, inwhich the first digit of each reference numeral identifies the figure inwhich the corresponding item is first introduced and in which:

FIG. 1 is a perspective view of a liner sheet, according to oneembodiment of the present invention, being inserted into a shippingcontainer;

FIG. 2 is a simplified schematic diagram of major and optionalcomponents of a monitoring system, according one embodiment of thepresent invention;

FIG. 3 is a perspective view of one context in which embodiments of thepresent invention can be advantageously practiced;

FIG. 4 is a perspective view of two liner sheets connected together,according to another embodiment of the present invention;

FIG. 5 is a perspective view of a six-panel, hinged liner sheet,according to another embodiment of the present invention;

FIG. 6 is a perspective view of two modular liner units, according toanother embodiment of the present invention;

FIG. 7 is a perspective view of a flexible, rollable liner sheet,according to another embodiment of the present invention;

FIG. 8 is a perspective view of an aircraft container, in which anembodiment of the present invention can be advantageously practiced;

FIG. 9 is a perspective view of a box liner, according to anotherembodiment of the present invention;

FIG. 10 is an exploded view of a rigid panel, according to oneembodiment of the present invention;

FIG. 11 is a simplified flowchart illustrating a process for fabricatinga liner sheet, such as the one illustrated in FIG. 10;

FIG. 12 is a perspective view of a fabric embodiment of a liner sheet,according to one embodiment of the present invention;

FIG. 13 is a perspective view of a liner sheet panel with an opticalfiber attached to its surface, according to one embodiment of thepresent invention;

FIGS. 14 and 15 are plan views of liner sheets, each having more thanone optical fiber, according to two embodiments of the presentinvention;

FIGS. 16, 17, 18 and 19 are plan views of liner sheets, each having oneoptical fiber, according to four embodiments of the present invention;

FIG. 20 is a perspective view of a liner sheet having more than oneoptical fiber, according to one embodiment of the present invention;

FIG. 21 is a simplified schematic diagram of the liner sheet of FIG. 14and associated circuitry, according to one embodiment of the presentinvention;

FIG. 22 is a simplified schematic diagram of the liner sheet of FIG. 14and associated circuitry, according to another embodiment of the presentinvention;

FIG. 23 is a simplified flowchart of a method of monitoring a container,according to one embodiment of the present invention;

FIGS. 24 and 25 are simplified schematic diagrams of major components ofmonitoring systems, according other embodiments of the presentinvention;

FIG. 26 is an exploded perspective view of a set of liner sheets,according to another embodiment of the present invention;

FIG. 27 is a plan view of the liner sheets of FIG. 26 laid flat;

FIG. 28 is a top view of a portion of the liner sheets of FIG. 26;

FIG. 29 is an enlarged view of a portion of the top view of FIG. 28;

FIG. 30 is a diagram of an alternative embodiment to the one show inFIG. 29; and

FIG. 31 is an exploded perspective view of a liner sheet attached to afence, according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The contents of U.S. patent application Ser. No. 10/981,836, titled“Tamper Proof Container,” filed Nov. 5, 2004; U.S. patent applicationSer. No. 10/837,883, titled “Tamper Proof Container,” filed May 3, 2004;and U.S. Provisional Application No. 60/535,449, titled “Tamper ProofContainer,” filed Jan. 9, 2004, are all hereby incorporated by referenceherein.

The present invention provides methods and apparatus to detect tamperingwith a six-sided or other type of container or box or other surface or asource of radiation within or near the container, box or surface, aswell as methods of manufacturing such apparatus. A preferred embodimentdetects a breach in a monitored surface of a container, box or fence orradiation from a source. A liner sheet lines at least a portion of aninterior surface of the container, box or fence, such that a breach ofthe portion of the container interior surface or fence damages the linersheet or radiation from the source impinges on at least a portion of theliner sheet. The liner sheet defines an optical path extending across atleast a portion of the sheet. For example, an optical fiber can be woveninto, or sandwiched between layers of, the liner sheet. The optical pathis monitored for a change in an optical characteristic of the opticalpath. For example, a light source can illuminate one end of the opticalfiber, and a light sensor can be used to detect the illumination, or achange therein, at the other end of the optical fiber. If the container,box or fence surface is breached, one or more portions of the opticalfiber are severed or otherwise damaged, and the optical path is brokenor altered. If radiation, such as gamma rays, irradiates all or aportion of the optical fiber, the transmissibility of irradiatedportion(s) of the optical fiber changes, and the optical path isaltered. The detected change in the optical path can be used to triggeran alarm, such as an annunciator. In addition, a message can be sent,such as by a wireless communication system and/or the Internet, to acentral location, such as a ship's control room or a port notificationsystem. In some embodiments, as little as a single nick, cut, pinch,bend, compression, stretch, twist or other damage to the optical fibercan be detected, thus a change in the light transmissibilitycharacteristic of a single optical fiber can protect the entire volumeof the container or box.

Embodiments of the present invention can be used in containers typicallyused to transport cargo by truck, railroad, ship or aircraft. FIG. 1illustrates an embodiment of the present invention being inserted intoone such container 100. In this example, the container 100 is an ISOstandard container, but other types of containers or boxes can be used.The embodiment illustrated in FIG. 1 includes a rigid, semi-rigid orflexible panel 102 sized to correspond to an interior surface, such asan inside wall 104, of the container 100. The panel 102 can be slid intothe container 100 and optionally attached to the inside wall 104, suchas by eyelets or loops (not shown) on the panel and hooks, screws,bolts, toggles or other suitable fasteners (not shown) on the insidewall. Other attachment mechanisms, such as adhesives or hook-and-pilesystems (commercially available under the trade name Velcro®) are alsoacceptable. In this manner, the panel 102 can later be removed from thecontainer 100. In any case, the panel 102 can be removeably attached tothe inside wall 104 or it can be permanently or semi-permanentlyattached thereto. Optionally, additional panels (not shown) can beattached to other interior surfaces, such as the opposite wall, ceiling,floor, end or doors, of the container 100. All these panels can beconnected to a detection circuit, as described below. Alternatively, thecontainer 100 can be manufactured with integral panels pre-installedtherein.

As noted, the panel 102 is preferably sized to correspond to the surfaceto which it is to be attached. For example, an ISO standard 20-footcontainer has interior walls that are 19.3 ft long and 7.8 ft high. (Alldimensions are approximate.) Such a container has a 19.3 ft. long by 7.7ft wide floor and ceiling and 7.7 ft wide by 7.8 ft. high ends. An ISOstandard 40-foot container has similar dimensions, except each longinterior dimension is 39.4 ft. ISO standard containers are alsoavailable in other lengths, such as 8 ft., 10 ft., 30 ft. and 45 ft.Containers are available in several standard heights, including 4.25 ft.and 10 ft. Other embodiments can, of course, be used with other sizecontainers, including non-standard size containers. The panel 102 ispreferably slightly smaller than the surface to which it is to beattached, to facilitate installation and removal of the panel.

The panel 102 includes an optical fiber 106 extending across an area ofthe panel. The optical fiber 106 can be positioned serpentine- orraster-like at regular intervals, as indicated at 108. A “pitch” can beselected for this positioning, such that the spacing 108 betweenadjacent portions of the optical fiber 106 is less than the size of abreach that could compromise the security of the container.Alternatively, the optical fiber 106 can be distributed across the panel102 according to another pattern or randomly, examples of which aredescribed below. In other embodiments, the panel 102 can be eliminated,and the optical fiber can be permanently or removeably attached directlyto the interior surface of the container 100. For example, adhesive tapecan be used to attach the optical fiber to the interior surface. Theoptical fiber can be embedded within the adhesive tape and dispensedfrom a roll, or the optical fiber and adhesive tape can be separateprior to installing the optical fiber. In yet other embodiments, thecontainer 100 is manufactured with optical fibers attached to itsinterior surfaces or sandwiched within these surfaces.

Optical connectors 110 and 112 are preferably optically attached to theends of the optical fiber 106. These optical connectors 110 and 112 canbe used to connect the panel 102 to other panels (as noted above and asdescribed in more detail below) or to a circuit capable of detecting achange in an optical characteristic of the optical fiber. The opticalconnectors 110 and 112 can be directly connected to similar opticalconnectors on the other panels or the detector circuit. Alternatively,optical fiber “extension cords” can be used between the panel and theother panels or detector circuit.

As noted, a detector circuit is configured to detect a change in anoptical characteristic of the optical fiber 106. As shown in FIG. 2, oneend of the optical fiber 106 is optically connected (such as via opticalconnector 110) to a visible or invisible light source 200. The other endof the optical fiber 106 is connected to a light detector 202. The lightsource 200 and light detector 202 are connected to a detector circuit204, which is configured to detect a change in the opticalcharacteristic of the optical fiber 106. For example, if the lightsource 200 continuously illuminates the optical fiber 106 and theoptical fiber is severed or otherwise damaged as a result of a breach ofthe container 100, the light detector 202 ceases to detect theillumination and the detector circuit 204 can trigger an alarm.Similarly, the detector circuit 204 can detect a decrease in, orcomplete loss of, light transmissibility of the optical fiber 106 as aresult of the optical fiber being irradiated, such as by gamma rays froma radiological weapon stored in or near the optical fiber. Thus, thedetector circuit 204 can trigger the alarm if the optical characteristicchanges by a predetermined amount. Optical characteristic changesinclude, without limitation, intensity, frequency, phase, coloration ofoptical fiber dopants and self-annealing properties of optical fiberthat has been irradiated.

The change in the optical characteristic need not be a total change. Forexample, in transit, as cargo shifts position within the container 100,some cargo might partially crush, compress, twist, stretch or stress thepanel 102 and thereby reduce, but not to zero, the light-carryingcapacity of the optical fiber 106. To accommodate such a situationwithout sounding a false alarm, the detector circuit 204 can trigger thealarm if the amount of detected light falls below, for example, 30% ofthe amount of light detected when the system was initially activated.Optionally, if the system detects a reduction in light transmission thatdoes not exceed such a threshold, the system can send a signalindicating this reduction and warning of a likely shift in cargo or someenvironmental deterioration of the panel, as opposed to a breach of thecontainer 100.

As noted, a system according to the present disclosure can be used todetect radiation from a source within or near a container. In such asystem, an optical characteristic of the optical fiber is changed byradiation incident on the fiber, and this changed optical characteristicis detected. For example, if an optical fiber is exposed to nuclearradiation, the light transmissibility of the optical fiber is reducedover time due to darkening of the optical fiber. The radiation may be ofvarious types, including alpha, beta, neutron, gamma or certain othertypes of electromagnetic radiation.

The light transmissibility of an optical fiber is reduced if the opticalfiber is exposed to ionizing radiation, such as nuclear radiation.Radiation-induced absorption (RIA) induces ionization and creates colorcenters in the optical fiber, thereby reducing the opticaltransmissibility of the fiber. This “radiation-induced darkening” (whichattenuates light signals) is cumulative over time, leading to atime-integration effect. Thus, even a low radiation dose rate over amulti-day trans-Atlantic journey would cause a detectable reduction inthe transmissibility of the optical fiber. If an optical fiber that hasbeen partially darkened by radiation is to be reused, the detectorcircuit 204 can calibrate itself to the fiber's then-currenttransmissibility when a panel containing the fiber is sealed in asubsequent container. The detector circuit 204 measures the amount oflight the optical fiber transmits, and the detector triggers the alarmif it detects a further attenuation of the transmitted light.Alternatively, the radiation-darkened optical fiber can be discarded.

The degree of radiation need not necessarily be measured. Instead, onlythe presence or absence of radiation above a threshold can be detectedto indicate the presence of a radioactive or other radiation emittingmaterial or device. Thus, a system according to the present disclosurecan provide a binary (Yes/No) indication of the presence of radiation.Optionally, the amount of darkening of the fiber or the rate ofdarkening can be used to estimate the strength of the radiation sourceor its distance from the panel(s). Such measurements from a number ofcontainers can be used to estimate the location of a container, amongmany containers, that houses a radiation source. For example, if anumber of systems (that are roughly aligned along a line) detectprogressively higher levels of radiation, the source of the radiation islikely to lie along the line in the direction of the higher radiationlevel. If two or more such lines (roughly) intersect, the radiationsource is likely to lie at the intersection.

Panels lining a typical ISO container can include as much as fourkilometers or more of optical fiber. Because light travels the entirelength of each optical path, the attenuation of this light isproportional to the sum of the lengths of all the darkened portions ofthe optical fibers that make up the optical path. Thus, even a smallamount of radiation-induced darkening along some or all parts of theoptical fiber(s) “adds up” to a detectable change in transmissibility ofthe fiber. Furthermore, even if a radiation source is partiallyshielded, such that only portions of the panels are irradiated, thesystem can detect the radiation source, because it does not matter whichportion(s) of the optical fiber are irradiated.

Some optical fibers are more sensitive to radiation-induced absorptionthan other optical fibers. Optical fiber manufacturers and others haveendeavored to develop optical fibers that are less sensitive toradiation-induced absorption, such as for use in outer space, nuclearreactors and particle accelerators. These manufacturers and others havepublished information comparing the sensitivities of various opticalfibers to radiation-induced absorption, as well as techniques for makingoptical fibers that are less sensitive to RIA. However, thesepublications teach away from the present invention, in that systemsaccording to the present disclosure preferably use optical fibers thatare more sensitive to RIA.

Various techniques can be used to increase the sensitivity of opticalfibers to radiation-induced absorption.

The amount of radiation-induced attenuation experienced by a lightsignal carried over an optical fiber depends on the wavelength of thesignal, the type of optical fiber (single mode, multi-mode,polarization-maintaining, etc.), manufacturer, model and other factors.The wavelength of the light source 200 (FIG. 2) is preferably selectedto maximize the sensitivity of the optical fiber to radiation-induceddarkening. Some optical fibers have two relative maximum attenuationpeaks, such as at about 472 nm and about 502 nm. Other optical fibershave more than two relative maximum attenuation peaks, such as at about470 nm, about 502 nm, about 540 nm and about 600 nm. Most optical fibersexhibit greater attenuation at shorter wavelengths than at longerwavelengths over the working optical spectrum, thus shorter opticalwavelengths are preferred. For example, if a single-wavelength lightsource is used, any wavelength (up to about 1625 nm or longer) can beused, however a shorter wavelength is preferred. Examples of acceptablewavelengths include about 980 nm, about 830 nm, about 600 nm, about 540nm, about 502 nm and about 472 nm, although other relatively shortwavelengths are acceptable.

Other factors, such as manufacturer and model, can also be selected formaximum sensitivity to radiation-induced darkening. For example, opticalfiber available from Corning under part number SMF-28 exhibitsacceptable radiation-induced darkening characteristics. Single mode,multi-mode, polarization-maintaining and other types of optical fibersare acceptable.

Alternatively, a difference in the attenuations of short-wavelength andlong-wavelength light components passing through the optical fiber canbe used to trigger a detector circuit 204 b, as shown in FIG. 24. If amulti-wavelength light source 200 c (such as an incandescent lamp) isused, light 2400 that reaches the far end of the optical fiber 106 issplit by a beam splitter 2402. One portion of the split beam passesthrough a first filter 2404 that passes short-wavelength light, which isthen detected by a light sensor 202 c. Another portion of the split beampasses through a second filter 2406 that passes long-wavelength light,which is then detected by a second light sensor 202 d. For example, thefirst filter can pass light having a wavelength less than about 980 nm,and the second filter can pass a light having a wavelength greater thanabout 980 nm. A difference signal 2408 is produced by a differentialamplifier 2410 from outputs of the two light sensors 202 c and 202 d. Ifthe optical fiber 106 is darkened by radiation, this darkening would bemore pronounced at short wavelengths than at long wavelengths, thus theoutput signal from the first (short wavelength) light sensor 202 c wouldbe less than the output signal from the second (long wavelength) lightsensor 202 d, and the difference between the signals from the lightsensors would be detected by the differential amplifier 2410. Justbefore or after sealing a container, the difference between the signalsis noted and stored, such as in a memory (not shown) in the detectorcircuit 204 b. Later, if the difference between the signals increases,for example if the difference exceeds a predetermined threshold, thealarm is trigger.

Of course, the differential amplifier 2410 can be replaced by anycircuit or software that compares the signals from the light sensors 202c and 202 d or calculates a difference between the signals. For example,two digital-to-analog converters (DACs) can be respectively connected tothe light sensors 202 c and 202 d, and outputs from the DACs can bedigitally compared or one of the outputs can be digitally subtractedfrom the other output, and the difference can be compared to a thresholdvalue.

Alternatively, as shown in FIG. 25, one of the filters can be omitted.In this case, the filter 2404 passes short-wavelength light, which isdetected by the light sensor 202 c to produce a short-wavelength signalS, as discussed above. The other light sensor 202 e is unfiltered, thusit detects both short-wavelength light and long-wavelength light toproduce a short- and long-wavelength signal (S+L). A first differentialamplifier 2500 produces a difference signal (S+L)−S=L that representsthe amount of long-wavelength light emerging from the optical fiber 106.A second differential amplifier 2408 operates as discussed above toproduce a signal that represents the difference between the amount ofshort-wavelength and long-wavelength light emerging from the opticalfiber 106.

Thermal annealing can release charges trapped within an optical fiber,thus at least partially reversing the effect of radiation-inducedabsorption. However, this thermal annealing can not occur at coldtemperatures, such as those likely to be encountered during anocean-going voyage in cool climates. To minimize the temperature of acontainer, and thus minimize thermal annealing of the optical fiber, thecontainer can be loaded low in the hold of a ship or below othercontainers to reduce or eliminate sunlight shining on the container. Theaverage temperature of the container is preferably kept less than orequal to about 25° C.

Some published information suggests using radiation-induced attenuationto measure radiation in optical fiber-based dosimeters, however suchsystems rely on thermal annealing to enable the optical fiber to quicklyrecover after being irradiated and be used for subsequent measurements.Thus, these publications teach selecting or constructing optical fibersthat exhibit good recovery characteristics. These publications teachaway from the present invention, in that systems according to thepresent disclosure preferably use optical fibers that have poor recoverycharacteristics and/or are operated so as to minimize or preventrecovery.

Radiation sensitivity of optical fiber is highly dependent on dopantsused in the manufacture of the fiber. Typical dopants include erbium,ytterbium, aluminum, phosphorus and germanium. Dopants, such asphosphorus, that increase the index of refraction of the core of thefiber are particularly influential in increasing the radiationsensitivity of optical fiber. Radiation sensitivity increases witherbium content. In addition, greater aluminum content in the core of anerbium-doped optical fiber increases the sensitivity of the fiber toradiation-induced effects. For example, an optical fiber doped withabout 0.18 mol % Yb, about 4.2 mol % Al₂O₃ and about 0.9 mol % P₂O₅exhibits an order of magnitude more attenuation than an optical fiberdoped with almost the same amounts of Yb and P₂O₅ but only about 1.0 mol% Al₂O₃.

Lanthanum can also be used as a dopant. For example, an optical fiberdoped with about 2.0 mol % La and about 6.0 mol % Al₂O₃ is extremelysensitive to radiation-induced effects, compared to Yb-doped andEr-doped optical fibers. The optical fiber preferably includes one ormore of the dopants listed above to increase or maximize its sensitivityto radiation.

Ytterbium-doped optical fiber and germanium-doped optical fiber canbecome “saturated” with radiation-induced absorption. When saturated,the annealing affects and the radiation-induced trapped charges balance,such that the radiation-induced attenuation reaches a constant value,even in the face of increasing total radiation dosage (at a constantdose rate). The predetermined amount, by which the opticalcharacteristic must change before the detector circuit 204 triggers thealarm, should take into account this saturation. Thus, the detectorcircuit 204 triggers the alarm preferably before the optical fiberbecomes saturated.

Fluorine and boron are sometimes used to lower the index of refractionof optical fiber cladding. When it is used to dope the core of anoptical fiber, fluorine increases radiation resistance, so opticalfibers without fluorine or with minimal fluorine in the core arepreferred.

Naturally-occurring, background ionizing radiation, which measures about300 millirems per year in the United States, can have a long-term effecton the transmissibility of optical fiber. The detector circuit 204 canaccount for a slow degradation in the optical fiber's transmissibilityas a result of this background radiation, so the detector circuit doesnot generate false alarms.

Gamma radiation easily penetrates the metallic walls of shippingcontainers. Thus, a system disposed within one container can detectradiation from a source within the container, as well as from a sourcein a nearby container, even if the nearby container is not equipped withits own radiation detection system. In transit, containers are typicallystacked side-by-side and on top of one another, as shown in FIG. 3.Thus, gamma radiation from one container is likely to be detected bysystems in adjacent containers. The number and positions of the adjacentcontainers where radiation is detected depend on several factors,including the strength of the radiation source, the number andthicknesses of intervening metallic walls of other containers and thetime-integration period over which the radiation impinges on the opticalfibers. Even if the container that houses the radiation source is notequipped with a radiation detection system, the locations and pattern ofcontainers whose systems detect radiation (and optionally the amount ofradiation detected by the respective systems) can be used to identifythe location of the radiation-emitting container.

Returning to FIG. 2, the detector circuit 204 and other components ofthe tamper detection system that reside in the container 100 can bepowered by a battery, fuel cell, thermocouple, generator or othersuitable power supply (not shown). Preferably, the power supply isdisposed within the protected portion of the container, so the powersupply is protected by the tamper detection system. A reduced lightsignal can forewarn of a pending failure of the power supply or attemptat defeating the tamper detection system. If power is lost, anappropriate fail/safe alarm signal can be sent.

Alternatively, rather than continuously illuminating the optical fiber106, the detector circuit 204 can control the light source 200 toprovide modulated or intermittent, for example pulsed, illumination tothe optical fiber 106. In this case, if the light detector 202 ceases todetect illumination having a corresponding modulation or intermittentcharacter, or if the light detector detects light having a differentmodulation or a different intermittent character, the detector circuit204 can trigger the alarm. Such non-continuous illumination can be usedto thwart a perpetrator who attempts to defeat the tamper detectionsystem by illuminating the optical fiber with a counterfeit lightsource.

The detector circuit 204 can be connected to an alarm 206 located withinthe container 100, on the exterior of the container, or elsewhere. Thealarm 206 can be, for example, a light, horn, annunciator, displaypanel, computer or other indicator or a signal sent over a network, suchas the Internet. Optionally, the detector circuit 204 can be connectedto a global positioning system (GPS) 208 or other location determiningsystem. If so connected, the detector circuit 204 can ascertain andstore geographic location, and optionally time, information when itdetects a breach or radiation or periodically. The detector circuit 204can include a memory (not shown) for storing this information. Thedetector circuit 204 can also include an interface 209, such as akeypad, ID badge reader, bar code scanner or a wired or wireless link toa shipping company's operations computer, by which informationconcerning the cargo of the container 100 can be entered. Thisinformation can include, for example, a log of the contents of thecontainer 100 and the locations of the container, when these contentswere loaded or unloaded. This information can also include identities ofpersons who had access to the interior of the container 100. Suchinformation can be stored in the memory and provided to other systems,as described below.

Optionally or in addition, the detector circuit 204 can be connected toa transmitter 210, which sends a signal to a receiver 212 if thedetector circuit detects a change in the optical characteristic of theoptical fiber 106. An antenna, such as a flat coil antenna 114 (FIG. 1)mounted on the exterior of the container 100, can be used to radiate thesignal sent by the transmitter 210. The receiver 212 can be located in acentral location or elsewhere. In one embodiment illustrated in FIG. 3,the container 100 is on board a ship 300, and the receiver 212 islocated in a control room 302 of the ship. Returning to FIG. 2, thereceiver 212 can be connected to an alarm 214 (as described above)located in a central location, such as the ship's control room 302, orelsewhere.

Some ships are equipped with automatic wireless port notificationsystems, such as the Automatic Identification System (AIS), that notifya port when such a ship approaches the port. Such a system typicallyincludes an on-board port notification system transmitter 216 and areceiver 218 that is typically located in a port. The present inventioncan utilize such a port notification system, or a modification thereof,to alert port officials of a breached container or a container in ornear which radiation has been detected and optionally of pertinentinformation concerning the container, such as its contents, priorlocations, times of loading/unloading, etc. The receiver 212 can storeinformation it has received from the transmitter 210 about anycontainers that have been breached in transit or in which radiation hasbeen detected. This information can include, for example, an identity ofthe container, the time and location when and where the breach occurredor radiation was detected, etc. The receiver 212 can be connected to theport notification transmitter 216, by which it can forward thisinformation to the port at an appropriate time or to a terrorismmonitoring system in real time. Other communication systems, such assatellite communication systems or the Internet, can be used to forwardthis information, in either real time or batch mode, to other centrallocations, such as a shipping company's operations center.

Alternatively or in addition, the transmitter 210 can communicatedirectly with a distant central location, such as the port or theshipping company's operations center. In such cases, a long-rangecommunication system, such as a satellite-based communications system,can be used. In another example, where the container is transported overland or within range of cellular communication towers, cellularcommunication systems can be used. Under control of the detector circuit204, the transmitter 210 can send information, such as the identity ofthe container and the time and location of a breach or radiationdetection, to the central location. Optionally, the transmitter 210 cansend messages even if no breach or radiation has been detected. Forexample, the detector circuit 204 can test and monitor the operationalstatus of the tamper detection system. These “heart beat” messages canindicate, for example, the location and status of the tamper detectionsystem, such as condition of its battery or status of an alternate powersupply, such as remaining life of a fuel cell, or location of thecontainer. Such periodic messages, if properly received, verify thatcomponents external to the container, such as the antenna 114, have notbeen disabled.

As noted above, and as shown in FIG. 4, several liner sheets, examplesof which are shown at 400 and 402, can be connected together to monitorseveral interior surfaces of a container or to monitor a large area of asingle surface. These liner sheets 400–402 preferably include opticalconnectors 404, 406, 408, and 410. Optical paths, for example thoseshown at 412 and 414, defined by the liner sheets 400–402 can beconnected together and to the detector circuit 204 and its associatedcomponents (shown collectively in a housing 416) via the opticalconnectors 404–410. Optical fiber “extension cords” 418 and 420 can beused, as needed. If the optical paths 412–414 were connected together inseries, a breach of any liner sheet 400 or 402 would trigger an alarm.

The intensity of the input light and the sensitivity of the detector canbe such that no amplifiers or repeaters are necessary along the opticalpath for a simple yes/no determination of breach of the container.Alternatively, each panel or a group of panels can have a respectiveoptical path and associated light source and detector, such that abreach of the optical path of the container panels can be identifiedwith a particular panel or side of the container.

In another embodiment illustrated in FIG. 5, a single liner sheet 500can include several hinged panels 502, 504, 506, 508, 510, and 512. Thepanels 502–512 can be folded along hinges 514, 516, 518, 520, and 522(as indicated by arrows 524, 526, 528, and 530) to form athree-dimensional liner for a container. Once folded, the liner sheet500 can, but need not, be self-supporting and thus need not necessarilybe attached to the interior surfaces of the container. For example,hinged panel 512 (which corresponds to a side of the container) canattach to hinged panel 508 (which corresponds to a ceiling of thecontainer) by fasteners (not shown) mounted proximate the respectiveedges of these panels. Similarly, hinged panels 502 and 510 (whichcorrespond to ends of the container) can attach to hinged panels 506,508, and 512.

Preferably, the hinged panels 502–512 are each sized according to aninterior surface of a container, although the panels can be of othersizes. Before or after use, the liner sheet 500 can be unfolded andstored flat. Optionally, the liner sheet 500 can be folded alongadditional hinges (such as those indicated by dashed lines 532, 534, and536) for storage. These additional hinges define hinged sub-panels.

As shown, optical fibers in the hinged panels 502–512 (such as thoseshown at 538, 540, and 542) can be connected together in series byoptical jumpers (such as those shown at 544 and 546). A single set ofoptical connectors 548 can be used to connect the liner sheet 500 to adetector circuit or other panels. Alternatively, additional opticalconnectors (not shown) can be connected to ones or groups of the opticalfibers. The liner sheet 500 has six panels 502–512 to monitor the sixinterior surfaces of a rectangular container. Other numbers and shapesof panels are acceptable, depending on the interior geometry of acontainer, the number of surfaces to be monitored, and the portion(s) ofthese surfaces to be monitored. It is, of course, acceptable to monitorfewer than all the interior surfaces of a container or less than theentire area of any particular surface.

As noted, ISO standard containers are available in various lengths. Manyof these lengths are multiples of 10 or 20 feet. To avoid stocking linersheets for each of these container lengths, an alternative embodiment,illustrated in FIG. 6, provides modular liner units, such as those shownat 600 and 602. The modular liner units 600–602 can include four (oranother number of) hinged panels, as described above. Preferably, eachmodular liner unit 600–602 has a width 604 and a height 606 thatcorresponds to a dimension of a typical container. The length 608 of themodular units is chosen such that a whole number of modular units,placed end to end, can line any of several different size containers.For example, the length can be 9.8 feet or 19.8 feet. Such modular unitscan be easier to install than a single liner sheet (as shown in FIG. 5),because the modular units are smaller than a single liner sheet.

Each modular liner unit 600–602 preferably includes two sets of opticalconnectors 610 and 612, by which it can be connected to other modularunits or to a detector circuit. A “loop back” optical jumper 614completes the optical path by connecting to the optical connectors 612of the last modular unit 602.

As noted with respect to FIG. 4, several liner sheets can be connectedtogether to monitor several surfaces or to monitor a large area. Anothersuch embodiment is shown in FIG. 26. In this embodiment, three linersheets are interconnected to monitor the six interior surfaces of acontainer. One liner sheet 2600 is folded along two lines 2602 and 2604to form a U-shaped structure that lines the top, back and bottom of thecontainer. Another liner sheet 2606 lines the right side of thecontainer. A third liner sheet 2608 is folded along a line 2610 to forman L-shaped structure that lines the left side and front of thecontainer.

Optical fibers (not shown) in the first and second liner sheets 2600 and2606 are interconnected by optical connectors 2612 and 2614. Similarly,optical fibers in the first and third liner sheets 2600 and 2608 areinterconnected by optical connectors 2616 and 2618. Optical “extensioncords” (not shown) can be used, if necessary.

The fold along line 2610 forms a hinge, so the front portion of thethird liner sheet 2608 can pivot about the hinge, as shown by arrow2620. The front portion of the third liner sheet 2608 therefore acts asa door. The door is opened to load or unload cargo into or out of thecontainer. Once the cargo is loaded or unloaded and the front portion ofthe third liner sheet 2608 is closed, the door(s) of the container canbe closed.

The first, second and third liner sheets 2600, 2606 and 2608 are shownunfolded, i.e. laid out flat, in FIG. 27. The optical fibers areindicated by dotted lines 2716, 2718 and 2720. The dimensions of theliner sheets 2600, 2606 and 2608 can be selected according to the sizeof the container in which the liner sheets are to be used. For example,if the liner sheets are to be used in a 10 ft. long by 10 ft. wide by 10ft. high container, each dimension is about 10 ft. or slightly less toaccommodate installing the liner sheets in the container. For example,dimensions 2700 and 2702 are each slightly less than 10 ft., accordingto the width of the container; dimensions 2704, 2706 and 2708 are eachslightly less than 10 ft., according to the height of the container; anddimensions 2710, 2712 and 2714 are each slightly less than 10 ft.,according to the length of the container.

If the liners sheets 2600, 2606 and 2608 are to be used in a 20 ft. or40 ft. long container, dimensions 2710, 2712 and 2714 are increasedaccordingly. Similarly, if the liner sheets are to be used in a shorter,taller, wider or narrower container, the appropriate dimensions areadjusted accordingly.

Returning to FIG. 26, the detector circuit 204 discussed above withreference to FIG. 2 is enclosed in a housing 2622 attached near an uppercorner of the right liner sheet 2606. A second housing 2624 is mountednear an upper corner of the front portion (i.e. door) of the liner sheet2608. FIG. 28 is a top view of the right liner sheet 2606, the frontportion of the liner sheet 2608 and the housings 2622 and 2624 mountedthereto. FIG. 29 is an enlarged view of a portion 2800 of FIG. 28. Alight detector 202 is coupled to the optical fiber 2718 in the rightside liner sheet 2606. A light source 200 in the housing 2622 opticallycouples with an end of the optical fiber 2720 in the front portion ofliner sheet 2608.

When the front portion of liner sheet 2608 (i.e. the door) is closed,the housing 2624 attached thereto aligns the optical fiber 2720 in thefront portion of the liner sheet with the light source 200 in thehousing 2622 attached to the right side liner sheet 2606, therebyoptically coupling the light source 200 with the optical fiber 2720.Alignment pins 2904 projecting from the housing 2624 mate with recesses2906 in the other housing 2622 to facilitate aligning the light source200 and the optical fiber 2720. Alternatively, rather than including thealignment pins 2904, the housing 2624 can be cone shaped and configuredto mate with a cone shaped recess in the other housing 2622.

Of course, the functions of the light source 200 and the light detector202 can be interchanged. That is, the light source can be coupled to theoptical fiber 2718 in the right side liner sheet 2606, and the lightdetector can be coupled to the optical fiber 2720 in the front portionof the liner sheet 2608. Other configurations are also possible, aswould be evident to those of ordinary skill in the art.

Alternatively, rather than optically coupling the circuits in the twohousings 2622 and 2624, the circuits can be electromagnetically coupled.For example, as shown in FIG. 30, the housing 2622 includes a coil 3000that electromagnetically couples with a second coil 3002 in the otherhousing 2624 when the front portion (i.e. door) of the liner sheet 2608is closed. The first coil 3000 is provided with an AC signal. Due to theproximity of the two coils 3000 and 3002, an AC signal is induced in thesecond coil 3002, which is connected to a circuit 200 a. The circuit 200a rectifies the received AC signal and drives a light source coupled tothe optical fiber 2720.

A liner sheet or panel according to the present invention can beimplemented in various forms. For example, rigid, semi-rigid andflexible panels have been described above, with respect to FIGS. 1 and5. Panels can be manufactured from a variety of materials includingcardboard, foamboard, plastic, fiberglass or composite materials orwoven or non-woven fabric material. The optical fiber can be embedded inthe panel or placed on a panel surface and covered with a protectivecoating or sheet. FIG. 7 illustrates another embodiment, in which aliner sheet 700 is made of a flexible, rollable material. The linersheet 700 can be unrolled prior to installation in a container and laterre-rolled for storage. Such a flexible liner sheet can be attached andconnected as described above, with respect to rigid panels.

Although the present invention has this far been described for use inISO and other similar shipping containers, other embodiments van be usedin other types of shipping containers or boxes. For example, FIG. 8illustrates an LD3 container 800 typically used on some aircraftEmbodiments of the present invention can be sized and shaped for use inLD3, LD3 half size, LD2 or other size and shape aircraft containers orcontainers used on other types of transport vehicles or craft.

Yet other embodiments of the present invention can be used in shippingboxes, such as those used to ship goods via Parcel Post® service. Forexample, FIG. 9 illustrates a liner sheet 900 that can be placed insidea box. The liner 900 can include a control circuit 902 that includes thedetector circuit 204 (FIG. 2) and the associated other circuitsdescribed above. Such a liner sheet need not necessarily be attached tothe interior surfaces of a box. The liner sheet 900 can be merely placedinside the box. Optionally, the control circuit 902 can include a datarecorder to record, for example, a time and location of a detectedbreach. The control unit 902 can also include a transmitter, by which itcan notify a central location, such as a shipper's operations center ofits location and its breach and radiation status.

Furthermore, as noted, embodiments of the present invention are notlimited to rectangular containers, nor are they limited to containerswith flat surfaces. For example, liner sheets can be bent, curved,shaped or stretched to conform to a surface, such as a curved surface,of a container.

As noted, a liner sheet according to the present invention can beimplemented in various forms. FIG. 10 is an exploded view of oneembodiment of a panel 1000 having an optical fiber 1002 sandwichedbetween two layers 1004 and 1006. One of the layers 1004 or 1006 can bea substrate, upon which the other layer is overlaid. A groove, such asindicated at 1008, is formed in one of the layers 1006, such as byscoring, cutting, milling, stamping or molding. Optionally, acorresponding groove 1010 is formed in the other layer 1004. The opticalfiber 1002 is inserted in the groove(s) 1008(-1010), and the two layers1004–1006 are joined. Alternatively, the optical fiber can be moldedinto a panel or sandwiched between two layers while the layers are soft,such as before they are fully cured. Optionally, a surface (for examplesurface 1012) of one of the layers can be made of a stronger material,or it can be treated to become stronger, than the rest of the panel1000. Suitable materials for the surfaces include wood, rubber, carpetand industrial fabric or carpet. When the panel 1000 is installed in acontainer, this surface 1012 can be made to face the interior of thecontainer. Such a surface can better resist impact, and thus accidentaldamage, from cargo and equipment as the cargo is being loaded orunloaded.

FIG. 11 illustrates a process for fabricating a panel, such as the panel1000 described above. At 1100, one or more grooves are formed in asubstrate. At 1102, one or more grooves are formed in a layer that is tobe overlaid on the substrate. At 1104, an optical fiber is inserted inone of the grooves. At 1106, the substrate is overlaid with the layer.

Thus far, panels with optical fibers embedded within the panels havebeen described. Alternatively, as illustrated in FIG. 12, an opticalfiber 1200 can be woven into a woven or non-woven (such as spun) fabric1202. In addition, an optical fiber can be woven or threaded through ablanket, carpet or similar material. As noted above, and as illustratedin FIG. 13, an optical fiber 1300 can be attached to a surface 1302 of aflexible or rigid panel 1304.

As noted, a pitch or spacing 108 between adjacent portions of theoptical fiber 106 (FIG. 1) can be selected according to the minimum sizebreach in the container 100 that is to be detected. In the embodimentshown in FIG. 1, the spacing 108 is approximately equal to twice theradius of bend 116 in the optical fiber 106. However, many opticalfibers have minimum practical bend radii. If such an optical fiber isbent with a radius less than this minimum, loss of light transmissionthrough the bent portion of the optical fiber can occur. As shown inFIG. 14, to avoid such loss in situations where a pitch less than twicethe minimum bend radius is desired, two or more optical fibers 1400 and1402 can be can be interlaced. In such an embodiment, if N opticalfibers are used and each optical fiber is bent at its minimum radius,the spacing (e.g. 1404) between the optical fibers can be approximately1/N the minimum spacing of a single optical fiber. The optical fiberscan be approximately parallel, as shown in FIG. 14, or they can benon-parallel. For example, as shown in FIG. 15, the optical fibers 1500and 1502 can be disposed at an angle with respect to each other.Alternatively (not shown), two liner sheets can be used, one on top ofthe other, to line a single surface of a container. The optical fibersof these two liner sheets can, for example, be oriented at an angle toeach other, offset from each other or otherwise to provide a tighterpitch than can be provided by one liner sheet alone or to provideredundant protection, such as for especially sensitive cargo.

In another embodiment shown in FIG. 16, a single optical fiber 1600 canbe configured so loops, such as those shown at 1602, at the ends of theoptical fiber segments each occupy more than 180° of curvature and,thus, provide a reduced spacing. Other configurations of a singleoptical fiber providing a reduced spacing are shown in FIGS. 17, 18 and19.

As noted, more than one optical fiber can be included in each linersheet. FIG. 20 shows a liner sheet 2000 with two optical fibers 2002 and2004. As shown in FIG. 21, the optical fibers 2002, 2004 can beconnected to each other in series, and the respective optical fibers canbe connected to a single light source 200 and a single light detector202. Alternatively (not shown), the optical fibers 2002, 2004 can beconnected to each other in parallel, and the optical fibers can beconnected to a single light source and a single light detector.

In an alternative embodiment shown in FIG. 22, each optical fiber 2002,2004 can be connected to its own light source 200 a and 200 b(respectively) and its own light detector 202 a and 202 b(respectively). In this case, signals from the optical fibers 2002, 2004can be processes in series or in parallel by a detector circuit 204 a.

A parallel connection of the optical fibers 2002, 2004, or a parallelprocessing of the signals from the optical fibers, would tolerate somebreakage of the optical fibers without triggering an alarm. Suchbreakage might be expected, due to rough handling that the panels mightundergo as containers are loaded and unloaded. The amount of lighttransmitted by several parallel optical fibers depends on the number ofthe optical fibers that remain intact. Once a container is loaded, thesystem could sense which fibers are intact and ignore damaged or severedfibers. Alternatively, the system could sense the amount of light beingtransmitted and set that amount as a reference amount. Later, intransit, if the amount of transmitted light fell below the referenceamount, the system could signal a breach or shift in cargo, as discussedabove. Of course, not all the optical fibers need be used at one time.Some of the optical fibers can be left as spares and used if primaryoptical fibers are damaged.

Any of the above-described liner sheets or variations thereon can beused to monitor a container. FIG. 23 illustrates a process formonitoring a container. At 2300, at least one interior surface, or aportion thereof, is lined with an optical path-defining material. At2302, one end of the optical path is illuminated. At 2304, the other endof the optical path is monitored for a change in an opticalcharacteristic of the optical path.

The invention has been described in relation to closed (i.e. entirelysurrounded) containers, rooms and the like, however embodiments are alsoapplicable to protecting open areas, such as yards. For example, asshown in FIG. 31, a liner panel 3100 can be attached to a fence 3102,such as a chain link fence, to monitor the fence for breaches thereof orradiation near the fence. For example, the flexible liner sheetdescribed above with reference to FIG. 7 can be attached to the fence byany suitable fastener. For example, the liner sheet 3100 can includeeyelets, and the liner sheet can be attached to the fence by screws,twisted wires or the like. Alternatively, one or more flexible, rigid orsemi-rigid panels can be attached to the fence and interconnected inseries, as discussed above. A relatively long liner sheet attached to afence integrates nuclear radiation, as discussed above. Therefore, sucha liner sheet is sensitive to relatively low-level radiation in itsvicinity.

In an alternative implementation, a thin electrical wire or path can beutilized rather than the optical fiber described above. For example, athin electrical wire can be arranged in a zigzag path across the area ofa panel or woven into a fabric to provide breakage detection similar tothat of the fiber optic embodiment described above. An electrical signalor energy source and electrical detector detects a break in theconductive path.

While the invention has been described with reference to a preferredembodiment, those skilled in the art will understand and appreciate thatvariations can be made while still remaining within the spirit and scopeof the present invention, as described in the appended claims. Forexample, although some embodiments were described in relation toshipping containers used to transport cargo, these containers can alsobe used to store cargo in warehouses, yards and the like, as well asduring loading and unloading of the containers at a loading dock. Someembodiments were described in relation to shipping containers used onships, etc. These and other embodiments can also be used with shippingboxes and other types of containers. The invention can also be used todetect tampering with, or a break into or out of, a room of a structure,such as an office, vault or prison cell. The term “container” in theclaims is, therefore, to be construed broadly to include various typesof shipping containers and boxes, as well as rooms and open areas, suchas yards, that are surrounded by fences or the like. Functions describedabove, such as differential amplifiers, comparisons, triggers andalarms, can be implemented with discrete circuits, integrated circuitsand/or processors executing software or firmware stored in memory. Inaddition, the optical paths have been described as being created usingoptical fibers. Other mechanisms can, however, be used to create opticalpaths. For example, hollow tubes and mirrors or combinations oftechnologies can be used to define optical paths through panels.

1. A tamper detection system, comprising: a first rectangular linersheet having a first area and defining a fiber-optic path extendingacross at least a portion of the first area, the first liner sheetincluding two parallel foldable regions, each foldable region extendinglaterally across the smaller dimension of the rectangular liner sheet; asecond liner sheet having a second area and defining a fiber-optic pathextending across at least a portion of the second area; a thirdrectangular liner sheet having a third area and defining a fiber-opticpath extending across at least a portion of the third area, the thirdliner sheet including a foldable region extending laterally across thesmall dimension of the rectangular liner sheet, thereby defining ahingable portion of the third liner sheet; a coupler interconnecting thefiber-optic path of the first liner sheet and the fiber-optic path ofthe second liner sheet; and a coupler interconnecting the fiber-opticpath of the first liner sheet and the fiber-optic path of the thirdliner sheet.
 2. The tamper detection system of claim 1, furthercomprising a circuit operable to detect a change in a opticalcharacteristic of at least one of the first, second and thirdfiber-optic path.
 3. The tamper detection system of claim 1, furthercomprising: a light source optically connected to one end of the opticalpath through the first, second and third liner sheet; a light detectoroptically connected to to other end of the optical pat through thefirst, second and third liner sheet; and a circuit connected to thelight source and the light detector and operable to detect a change inan optical characteristic of at least one of the first, second and thirdfiber-optic path.
 4. The tamper detection system of claim 3, wherein theconnection between to light source and the end of the optical pathextends between the second liner sheet and the third liner sheet whenthe hingable portion of the third liner sheet is closed.
 5. The tamperdetection system of claim 3, wherein the connection between the lightdetector and the end of the optical path extends between the secondliner sheet and the third liner sheet when the hingable portion of thethird liner sheet is closed.
 6. The tamper detection system of claim 3,wherein the light source a electromagnetically coupled to the circuitwhen the hingable portion of the third liner sheet is closed.
 7. Thetamper detection system of claim 3, wherein the light detector iselectromagnetically coupled to the circuit when the hingable portion ofthe third liner sheet is closed.
 8. The tamper detection system of claim1, such that nuclear radiation impinging on the fiber-optic path of atleast one of the first, second and third liner sheet causes a change inan optical characteristic of the fiber-optic path.
 9. A tamper detectionsystem, comprising: a first rectangular liner sheet having a first areaand containing a fiber-optic path extending across at least a portion ofthe first area, the first liner sheet including two parallel hingableregions each hingable region extending laterally across the smallerdimension of the first rectangular liner sheet. a second liner sheethaving a second area and containing a fiber-optic path extending acrossat least a portion of the second area; a third rectangular liner sheethaving a third area and containing a fiber-optic path extending acrossat least a portion of the third area, the third liner sheet including ahingable region extending laterally across the small dimension of thethird rectangular liner sheet, thereby defining a door; a couplerinterconnecting the fiber-optic path of the first liner sheet and thefiber-optic path of The second liner sheet; and a couplerinterconnecting the fiber-optic path of the first liner sheet and thefiber-optic path of The third liner sheet.
 10. The tamper detectionsystem of claim 9, further comprising a circuit operable to detect achange in an optical characteristic of at least one of the first, secondand third fiber-optic path.
 11. The tamper detection system of claim 9,further comprising: a light source optically connected to one end of theoptical path through the first, second and third liner sheet; a lightdetector optically connected to the other end of the optical paththrough the first, second and third liner sheet; and a circuit connectedto the light source and the light detector and operable to detect achange in an optical characteristic of at least one of the first, secondand third fiber-optic path.
 12. The tamper detection system of claim 11,wherein the connection between the light source and the end of theoptical path extends between the second liner sheet and the third linersheet when the door of the third liner sheet is closed.
 13. The tamperdetection system of claim 11, wherein the connection between the lightdetector and the end of the optical pat extends between the second linersheet and the third liner sheet when the door of the third liner sheetis closed.
 14. The tamper detection system of claim 11, wherein thelight source is electromagnetically coupled to the circuit when the doorof the third liner sheet is closed.
 15. The tamper detection system ofclaim 11, wherein the light detector is electromagnetically coupled tothe circuit when the door of the third liner sheet is closed.
 16. Thetamper detection system of claim 9, such that nuclear radiationimpinging on the fiber-optic path of at least one of the first, secondand third liner sheet causes a change in an optical characteristic ofthe fiber-optic path.
 17. A tamper detection system, comprising: a firstliner sheet containing a fiber-optic path extending across at least aportion of the first sheet; a second liner sheet containing afiber-optic path extending across at least a portion of the secondsheet; at least one of the first and second liner sheets having at leastone hingable region extending laterally across the liner sheet to defineat least two foldable portions of the sheet; and a couplerinterconnecting the fiber-optic path of the first liner sheet and thefiber-optic path of the second liner sheet.
 18. The tamper detectionsystem of claim 17, further comprising a circuit operable to detect achange in an optical characteristic of at least one of the first andsecond fiber-optic path.
 19. The tamper detection system of claim 17,further comprising: a light source optically connected to one end of theoptical path through the first and second liner sheet; a light detectoroptically connected to the other end of the optical path through thefirst and second liner sheet; and a circuit connected to die lightsource and to light detector and operable to detect a change in anoptical characteristic of at least one of the first and secondfiber-optic pat.
 20. The tamper detection system of claim 17, such thatnuclear radiation impinging on the fiber-optic path of at least one ofthe first and second liner sheet causes a change in an opticalcharacteristic of the fiber-optic path.
 21. A tamper detection system,comprising: a first liner sheet having a first area and a fiber-opticpath extending across at least a portion of the first area, the firstliner sheet including at least one hingable region extending laterallyacross the first liner sheet to define at least two foldable portions ofthe first liner sheet; a second liner sheet having a second area and afiber-optic path extending across at least a portion of the second area;a third liner sheet having a third area and a fiber-optic path extendingacross at least a portion of the third area, the third liner sheetincluding at least one hingable region extending laterally across thethird liner sheet to define at least two foldable portions of the thirdliner sheet; a coupler interconnecting the fiber-optic path of the firstliner sheet and the fiber-optic path of the second liner sheet; and acoupler interconnecting the fiber-optic path of the first liner sheetand the fiber-optic path of the third liner sheet.
 22. The system ofclaim 21 wherein the optical fiber extends in a serpentine path acrosssubstantially the entire area of the first liner sheet.
 23. The systemof claim 22 wherein to spacing between adjacent portions of the opticalfiber is of a smaller size than a breach that could comprise thesecurity of a container.
 24. The system of claim 22 wherein the spacingbetween adjacent positions of the optical fiber is sufficiently small tocause breakage or degradation of the optical fiber in reaction to anattempted breach of the first liner sheet.
 25. The system of claim 21wherein: at least one of the couplers oft least one of the liner sheetsis operative to be coupled to a light source; and at least one of thecouplers of at least one of the liner sheets is operative to be coupledto a light detector.
 26. The system of claim 21, wherein: the firstliner sheet is rectangular; and the third liner sheet is rectangular.